The field of the invention relates to an apparatus for separating and removing particles from an aqueous carrier, such as a slurry or the like. More particularly, the field of the invention relates to a device and process for separating and concentrating particles according to their specific gravity for use in mining or soil remediation projects, or the like.
Economical restoration of contaminated soils and water to an environmentally acceptable condition is becoming a critical problem in many industrialized areas throughout the world. Conventional methods of removing contaminants such as heavy metals and other pollutants from soils and water-based slurries are expensive and often require the expenditure of large amounts of energy.
Conventional methods of soil and water remediation which focus on removing contaminants from water-based slurries or slurry materials have the disadvantage of a limited ability to process large amounts of contaminated soils, mine tailings, or the like.
Conventional methods which depend upon the separation of contaminants such as heavy metals from a slurry by screening the particles have the disadvantage of being unable to screen particles which fall below approximately 40 mesh in size. Thus, most conventional methods which rely upon a screening process to remove contaminants from soils or particles from a water-based slurry are incapable of solving the problem of soil or water remediation. These methods leave most of the smaller sized contaminants such as particles of lead, arsenic or the like in the soil or water.
Therefore, it is apparent that what is needed is an apparatus for large-scale removal of contaminants such as heavy metals, from water, water-based slurries, contaminated soils or the like. Such a method of large scale restoration of contaminated soils or water-based slurries to an environmentally acceptable condition should ideally be capable of substantially removing all of the heavy metal particles or other contaminants which exist in particulate form from water, a water-based slurry at, or other aqueous carrier at extremely high volume.
What is also needed is an apparatus capable of such large scale removal of particulate contaminants without the need for consuming large amounts of energy to effect such removal.
It would also be desirable if such an apparatus could also be applied for processing of mine slurries at high volumes for removing and separating various particles of ores or other material targeted for processing.
What is also needed is an apparatus for high volume selection of targeted particles according to their specific gravity or other unique characteristics which enables the particles to be separated not only from the slurry material, but from other particles. Such an apparatus ideally would be capable of separating and concentrating like kinds of particles at high volumes.
A side cross sectional view of a conventional particle separator which begins to solve these problems, and which was designed by the inventor of the current invention, is illustrated in FIG. 1. Referring to FIG. 1, particulate matter suspended in an aqueous carrier such as a slurry for mining operations or the like is introduced through a reservoir tank 2. The aqueous carrier and particulate matter is pumped into the reservoir tank 2 at a rate sufficient to keep it full so that constant pressure and supply is provided to the particle separator. The aqueous carrier and particulate matter spread across a circular dispersion plate 4 and travel radially outward along a series of concentric, annular steps 6. Each step has a drop flow opening 8, providing a path to a drop channel 10 full of the aqueous carrier.
The rate of flow of the aqueous carrier decreases as it spreads out over consecutively larger concentric steps. Thus, the flow rate is highest over the innermost step 6'. Only the densest particulate matter, having the highest specific gravity, drops through the drop flow opening 8 of the innermost step 6'. At each subsequent step consecutively less dense particulate matter drops through the drop flow openings 8.
The vertical sides 12 of the steps 6 serve dual purposes. First, they allow the force of gravity to act upon the aqueous carrier and provide the impetus for flow. This is an advantage over other conventional methods since less energy is used by the system. The vertical sides 12 also act as mixing means. As particulate matter passes over the horizontal part of each step 6, it begins to settle. The vertical part 12 of each step 6 mixes the particulate matter back into the aqueous carrier, promoting suspension of the particulate matter and avoiding settling.
Originally the drop channels 10 contained aqueous carrier but no flow path was provided through the drop channels; they were static. This had the disadvantage of providing a low yield and a low rate of throughput. Yield is critical because it is important to remove all contaminants. Throughput is critical for particle separators to economically remediate huge volumes of soil or water. In order to increase throughput, the rate of flow through the particle separator must be increased. However, increasing the rate of flow decreases the yield since more particulate matter is carried over the drop flow openings 8 at each step 6 of the particle separator.
One approach to solve this problem is to allow some flow through the drop channels 10, and to recycle matter captured in selected drop channels which are most likely to contain matter of a desired density. The matter in the selected drop channels is sent back through the particle separator in a separate run. This system has the disadvantage of having to make separate, non-continuous runs through the particle separator which is extremely costly and labor intensive. Further, this conventional recycling system, while providing higher yield, also causes scatter. In a single run at a low flow rate, matter of a desired density will be highly concentrated in a single drop channel. When the matter is run through twice at a higher flow rate, yield increases, but the matter of a desired density spreads among several drop channels 10, instead of being highly concentrated in a single drop channel. Thus, the desired matter is more often mixed with matter of other densities, reducing concentration. This is a serious disadvantage both for removing contaminants and for removing valuable ores. For removing contaminants, such as lead, it is desirable that there be a heavy concentration so the contaminant can be disposed of economically at high concentrations in low volume containers. For valuable ores, such as gold, there must be a threshold concentration for economical recovery processing.
Thus, what is needed is an apparatus and process for improved particle separation with increased throughput, and very low scatter, capable of separating and concentrating particles smaller than 40 mesh, potentially down to 50 microns.